有界空间内复杂液体介质中气泡相关的非线性声响应

In this project, we will explore the nonlinear oscillation of bubbles in finite space filled with mixed liquid medium, at the same time, the interaction of bubbles and surrounding medium will be taken into account. First, for the purpose of making clear the essential properties of bubbles, the the forced oscillation of bubbles will be researched for the condition that the tubes are of different radii, and the dynamics models will be introdeced in accordance with the motion modes of bubbles in tubes. Second, the interactions between bubbles and driving acoustic field, surrouding medium and tubes' wall will be studied using analytical methods and numerical methods in order to find a way which can be adopted to describe quantitatively cavitation effects in tubes. Third, the responses of elastic wall of tubes to oscillating bubbles, such as elastic deformation and rupture, will be taken into account. Based on the physical nature of material and structure of tubes, the mechanism of deformation and rupture will be researched, which can help us to ulderstand how to control the dose of ultrasound. Our main purposes is to develop the basic theories of nonlinear oscillation of single bubble or bubble clusters, and analyze the mechanism of interaction between bubbles and surrounding mediums. What we research will make an effort to give some advice to solve the problems related to the propagation of high-intensity ultrasound in biological tissue and blood.

本项目将研究超声波作用下有界空间内复杂介质中气泡的非线性振动规律，同时探讨气泡运动对周围介质的影响。第一，探讨不同管径内气泡的振动规律，建立管内气泡非线性动力学模型，研究管的存在对气泡振动模式的影响，以期找出气泡在管内振动的本质特征；第二，利用解析法和数值法探讨管内非线性振动气泡与声场、周围介质和管壁间的相互作用，目的在于寻找与管内非线性振动气泡相关的空化效应的定量描述方法；第三，分析弹性管壁对非线性振动气泡的响应，如弹性形变、破裂等，从管壁本身的物理特征出发研究强超声波作用下管壁破裂的物理机制，为控制超声剂量提供理论和实验基础。本项目的主要目的在于发展单气泡和泡群在管内非线性振动的基本理论，分析其在高强度超声波作用下同周围介质的相互作用机理，为解决高强度超声波在生物组织、血液等复杂介质中传输时遇到的声学问题作出应有的努力。

气泡非线性动力学行为的研究有利于调控空化场中气泡的运动和空化影响，同时也有利于控制包膜气泡在生物组织中的靶向运动，从而实现更高精度的超声诊断以及利用超声微泡进行靶向治疗等。.本项目研究了超声波作用下局域空间内一定聚集形态气泡的非线性振动规律，取得了一系列的成果，具体如下：.（1）发展了硬壁管道内运动气泡的动力学模型，并以此为基础开展了动力学分析，发现管道对气泡振动的约束降低了气泡的共振频率，有利于气泡低频共振声响应的实现。.（2）发展了弹性管壁和气泡的耦合振动动力学模型，考察了气泡非线性振动对管壁的影响以及气泡的非线性声响应特征的变化。由于耦合振动的影响，气泡的非线性声响性共振峰数目增加。.（3）发展了硬壁面管道内气泡间相互作用的动力学模型，分析了气泡间相互作用对气泡在管道内声响应状态的影响。结果表明，管尺寸以及气泡初始状态等因素对气泡的声响应具有较大影响。.（4）针对气泡的不同群聚状态发展了气泡群振动动力学模型，分析了群振动状态下气泡的动力学特征，发现气泡的群振动有利于增强空化效应。.基于以上工作，我们在本项目研究过程中发展了单气泡和泡群在管内非线性振动的基本理论，分析了气泡在高强度超声波作用下同周围介质的相互作用机理。完成了项目既定研究内容和目标。